1. Field of the Invention
The present invention relates to a method and device for searching a recording medium having a management information area whose location information is overlapped with the location information of a program area of the recording medium.
2. Description of the Related Art
In general, a disk-type recording medium such as, e.g., a CD-RW, has wobble recording tracks on which ATIP (Absolute Time in Pregroove)-framed data are stored during its manufacturing stage or prior to any data is recorded thereon by a user. As known, the ATIP-framed data are pre-encoded on the recording medium in a wobble shape by frequency modulation.
FIG. 1 shows an example of a general ATIP frame. Each ATIP frame carries certain bits of information. As shown in FIG. 1, if the first bits (M1, S1, and F1) of the ‘minutes’, ‘seconds’ and ‘frames’ fields of the ATIP frame is ‘000’, then these fields are considered to contain an ATIP time code. An ATIP time code is location information for the recording medium and is used to indicate a particular location on the recording medium at which data/information is stored.
FIG. 2 is a graph of an ATIP time code for a general writable disk. As shown in FIG. 2, an ATIP time code TC1 corresponding to a program area (data area) of the disk increases linearly from 0 (zero) to a maximum value of 79:59:74 in the outwardly direction of the disk. An ATIP time code TC2 corresponding to a lead-in area (management information area) of the disk decreases linearly from 99:59:74 to some value in the inwardly direction of the disk towards the disk center.
Generally, the management information area (MIA) including the lead-in area of the disk is about 4˜5 minutes in time code size where its time code ranges from about 95 to 99 minutes. On the other hand, the program area of the disk ranges from 0 to about 80 minutes in time code size because its recording capacity is about 80 minutes. Due to the gap between 80 minutes and 95 minutes in time code, the ATIP time code of the management information area of a general disk-type recording medium does not overlap with the ATIP time code of the program area (PA) of the recording medium. As a result, time codes have been used to distinguish between the management information area and the program area of the recording medium during data recording operations.
However, the storage capacity of a conventional disk-type recording medium is being expanded in these days due to the advancement of technology. Due to this effort, a recording medium having a recording capacity (program area) of 99 minutes has been introduced. But, such expansion of recording capacity introduces another problem to the recording medium. Due to the expanded capacity of the recording medium, the recording medium now has an overlapping time code range.
FIG. 3 shows a graph of ATIP time codes of a conventional, capacity-expanded writable disk, illustrating an overlapping range of the time codes between the program area and the management information area of the disk.
As shown in FIG. 3, there are an expanded ATIP time code TC1′ for the program area, and an ATIP time code TC2 for the management information area of the disk. The end part of the ATIP time code TC1′ of the program area of the disk is overlapped with the ATIP time code TC2 of the management information area of the disk, because the recording capacity of the disk has been expanded to 99:59:74 in time code.
The overlapped ATIP time codes cause certain serious problems. For instance, if an ATIP time code falls within the overlapped ATIP time code range, it often becomes difficult and impossible to know whether a current recording position of the disk is in the management information area or in the program area since the time code would equally apply to both the management information area and the program area. As a result, data can be written in the wrong area of the disk.
As an example of this problem, assume that a particular time address among 95˜99 minutes in ATIP time code is requested to a disk device to record information in the lead-in area of the disk at the requested time address. But, if an optical pickup slides erroneously to an outer program area having the time code of 95˜99 minutes during a track jump, then the information to be written in the lead-in area (management information area) would instead be recorded in the outer program area, which is completely undesired. Further, even if control signals have been applied to the optical pickup to move the pickup to the desired location in the lead-in area of the disk, if a servo fails then the pickup can be erroneously moved to the program area of the disk, which will result in the recording of the information in the wrong area because the requested time code has applicability both in the program area and the management information area of the disk.
In addition to the use of the ATIP time code as location information of the disk, another way to identify a particular location on the disk is to use an absolute time (MM:SS:FF). As known, when data are recorded on a recording medium such as a CD-Rom, an absolute time (MM:SS:FF) is written in a sub-Q channel of every data block. The absolute time is location information used to indicate locations on the recording medium. A distraction between the ATIP time code and the absolute time is that the ATIP time codes are carried inherently on the disk by the wobbling of the physical tracks on the disk, whereas the absolute times are recorded values made during a recording operation.
If a recording medium has an expanded 99-minute data recording capacity such that the absolute time in the program area of the recording medium has been extended up to (99:59:74) in absolute time, then the absolute time of the management information area of the recording medium will overlap with the absolute time of the program area of the recording medium, similar to what is shown in FIG. 3.
Generally, a disk device such as a recording/reproducing device cannot monitor the time codes of ATIP frames during a data reading (reproducing) because of the hardware structural limitations. Instead, the disk device is configured to monitor the absolute time written in the sub-Q channel of reproduced data. As a result, since the absolute times of the program area and the management information area of the disk overlap with each other as discussed above, then the problem of reading data to a wrong location on the disk can occur even if the correct absolute time has been identified.
For example, assuming that a host sent to a disk device a command to read data from an arbitrary position in the management information area of the disk. But, at this time, if an optical pickup slides erroneously to an outer program area (having the absolute time of 95˜99 minutes) during a track jump, then the disk device would read data from the undesired program area, instead of the desired management information area, whereby wrong information/data would be read and provided to the host.